Monogenic Diabetes

Monogenic diabetes is a lesser known form of diabetes that is often misdiagnosed as type 1 or type 2 diabetes. Monogenic diabetes occurs when there is a mutation of a single gene. There are around 30,000 individual genes in the body, and more than 20 genes are linked to diabetes. The most common forms of monogenic diabetes are neonatal diabetes and maturity onset diabetes of the young (MODY).

Neonatal diabetes (NDM) is a rare form of monogenic diabetes that occurs in the first 6 months of life. Approximately one in 100,000 to 500,000 live births will have neonatal diabetes. Often neonatal diabetes is misdiagnosed as type 1 diabetes, but type 1 diabetes typically occurs after the first 6 months of life. There are two types of neonatal diabetes, permanent neonatal diabetes (PNDM) and transient neonatal diabetes (TNDM). In TNDM the condition disappears during infancy and can reappear later in life. Many fetuses with NDM do not grow well in the womb and fail to gain weight and grow as rapidly as other infants. With appropriate diabetes therapy, growth and development can normalize.

MODY is diagnosed in 1-2% of people with diabetes. It is a highly inherited mutation, and typically patients present with a significant family history of diabetes. Frequently MODY diabetics have symptoms that are moderate or absent and are only diagnosed with diabetes after routine lab work. Younger healthier people are often misdiagnosed with type 1 diabetes, and overweight people are often misdiagnosed with type 2 diabetes. In cases where the person has a strong family history of diabetes, a genetic test will be performed to confirm MODY and the rest of the family should also be tested after a diagnosis.

Scientists are not sure why genetic mutations occur, but they do know that they can be either spontaneous or hereditary. Hereditary mutations are passed from parent to child and in this case they are not dependent on the sex of the parent. Spontaneous mutations occur during fetal development, and can become hereditary for the next generation.

Treatment for monogenic diabetes varies. Certain forms require no intervention as slightly elevated blood sugar levels are considered “normal” for the individual and will not lead to complications later. Many forms of monogenic diabetes are controlled with sulfonylureas or oral medication, and some will require insulin. Genetic testing can be done to determine what the best treatment for diabetes would be depending on the particular mutated gene.